Pima Indians have a high prevalence of obesity, diabetes mellitus and hyperinsulinemia, but they have low plasma cholesterol levels, reduced LDL synthesis, and decreased incidence of cardiovascular disease. Lipoprotein metabolism in Pima Indians will be investigated in order to further investigate lipoprotein metabolism in this population. Synthetic and catabolic rates for VLDL will be compared in groups having different insulin levels using tritiated glycerol as a precursor. VLDL metabolism will be studied in a group of diabetics to determine the influence of hyperglycemia on VLDL metabolism in this popultion. Conversion of VLDL to LDL will be studied in nondiabetics and diabetics using 131 I VLDL and 125 I LDL simultaneously in order to elucidate the mechanism of maintenance of maintenance of low LDL. Postheparin, muscle, and adipose tissue lipoprotein lipase levels will be measured. The results of this study should yield data on the control of lipoprotein metabolism in this population and explore the relation between these lipoproteins, diabetes and cardiovascular disease.